Every new app created with Xcode supports so called “FullScreen” out of the box. Just need to set NSWindow property.
This allows to switch from windowed mode to FullScreen on another desktop workspace or another display. It is great feature, if of course it is supported by application. Difference with other “fullscreen” modes in for example Windows x86 app (where full screen is just resized window), is that OS X fully controls window position and size, which is switched to a different workspace or display.
At this time, cocos2d-x/OS X does not seem to support this feature. For a user, this is additional button in right upper corner of the window, that let’s him switch to FullScreen mode.